Expandable interbody fusions devices

ABSTRACT

Expandable fusion devices, systems, instruments, and methods thereof. The expandable fusion implant may include an upper endplate assembly and a lower endplate assembly. The upper and lower endplate assemblies may be configured to expand in width. A rotatable actuator may move one or more driving ramps, which mate with an upper ramp and a lower ramp, respectively. The actuator may cause independent movement of one or more of the driving ramps, thereby causing an expansion in height of the upper and lower endplate assemblies.

FIELD OF THE INVENTION

The present disclosure relates to surgical devices, and moreparticularly, to expandable fusion devices capable of being deployedinside an intervertebral disc space and then expanded in width and/or inheight to maintain disc spacing, restore spinal stability, and/orfacilitate an intervertebral fusion.

BACKGROUND OF THE INVENTION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

Interbody devices have been used to provide support and stability in theanterior column of the spinal vertebrae when treating a variety ofspinal conditions, including degenerative disc disease and spinalstenosis with spondylolisthesis. Clinical treatment of spinalpathologies with anterior vertebral body interbody devices relies onprecise placement of the interbody device to restore normal anteriorcolumn alignment. Iatrogenic pathologies may result from the surgicalaccess window to the disc space, failure to precisely place theinterbody on hard cortical bone often found on the apophyseal ring ofthe vertebral body, and/or failure to precisely control and restorenormal anatomical spinal alignment.

As such, there exists a need for a fusion device capable of preciseplacement of interbody support that both increases interbody contactwith hard cortical bone and provides precise control of anterior columnalignment while reducing the profile of the access window to the discspace.

SUMMARY OF THE INVENTION

To meet this and other needs, and in view of its purposes, the presentapplication provides devices, systems, instruments, and methods forinstalling, and expanding the interbody implant in width and/or height.In particular, an expandable fusion device is provided, which has anarrow profile and may expand in width to increase surface area contactand/or has a reduced height and may expand in height to restoreanatomical spinal alignment. The expandable fusion device may have theability to individually adjust the anterior and posterior heights of theinterbody and to adjust sagittal balance correction. The device may beinstalled in an open, semi-open, or minimally invasive surgicalprocedure. The expandable fusion device may be capable of being placedinto the disc space down a guide tube or cannula, for example, widenedin width, and then expanded in height into an expanded configuration.The implant may also be configured to passively pivot about alongitudinal axis of the implant. The passive adjustment of theendplates may account for the mismatch of the oblique angle of insertionand/or the desired sagittal angle

According to one embodiment, an expandable implant includes an upperendplate assembly, a lower endplate assembly, an actuator assembly, aplurality of driving ramps, and upper and lower ramps mated with thedriving ramps. The upper endplate assembly may include a plurality ofupper endplates. The lower endplate assembly may include a plurality oflower endplates. The actuator assembly may include a rotatable actuatorhaving a shaft and a rotatable nut. The plurality of driving ramps mayinclude a front ramp, a mid-ramp, and a rear ramp positioned along theshaft of the actuator. The upper ramp may be connected to the upperendplate assembly and engaged with the plurality of driving ramps. Thelower ramp may be connected to the lower endplate assembly and engagedwith the plurality of driving ramps. The upper and lower endplateassemblies may be configured to expand in width. Rotation of theactuator and/or the nut may cause movement of one or more of the drivingramps, which press against the upper and lower ramps, thereby causing anexpansion in height of the upper and lower endplate assemblies.

In one embodiment, the plurality of upper endplates may include a firstupper outer endplate, a second upper outer endplate, and a third uppercentral endplate positionable between the first and second upper outerendplates. The plurality of lower endplates may include a first lowerouter endplate, a second lower outer endplate, and a third lower centralendplate positionable between the first and second lower outerendplates. The upper and lower central endplates may be configured toexpand the respective upper and lower outer endplates outwardly, therebyexpanding the overall width of the implant. One of the outer endplatesmay include an elongate groove and the other outer endplate may retain apin configured to be received within the elongate groove such that whenthe outer endplates move outwardly, the pin is guided along the path ofthe elongate groove. For example, the elongate groove may be a lineargroove that allows for a generally parallel expansion in width of theouter endplates. The central endplates may be configured to slidebetween the outer endplates on one or more tracks. When the centralendplate is advanced forward distally along the one or more tracks, theouter endplates expand in width.

The height of the implant may be expanded by an actuation assembly. Theshaft of the actuator may include a first threaded portion, a secondthreaded portion, and a non-threaded portion. The front driving ramp maybe positioned on the non-threaded portion of the actuator, the mid-rampmay be positioned on the first threaded portion, and the rear ramp maybe positioned on the second threaded portion. The first and secondthreaded portions may have different attributes, such as different outerdiameters, handedness, thread form, thread angle, lead, pitch, etc. Forexample, the first threaded portion may have a smaller outer diameterand different handedness than the second threaded portion. The rotatablenut may be configured to move the rear ramp independent of the mid-rampand front ramp.

The upper and lower endplate assemblies may be configured to passivelypivot about a longitudinal axis of the implant. For example, the outersurfaces of the upper and lower ramps may each define one or more slotsconfigured to guide one or more corresponding tabs on the inner cavitiesof the upper and lower central endplates, respectively. The slot mayinclude a circular t-slot configured to guide or pivot the centralendplates about the longitudinal axis of the implant. In this manner,the upper and lower endplate assemblies are able to pivot about thelongitudinal axis to passively account for the mismatch of the obliqueangle of insertion and/or the desired sagittal angle.

According to another embodiment, the implant system may include anexpandable implant and an inserter instrument. The implant may includean upper endplate assembly including a first upper outer endplate, asecond upper outer endplate, and a third upper central endplatepositionable between the first and second upper outer endplates. Theimplant may include a lower endplate assembly including a first lowerouter endplate, a second lower outer endplate, and a third lower centralendplate positionable between the first and second lower outerendplates. The implant may include an actuator assembly including arotatable actuator having a shaft and a rotatable nut. The implant mayinclude a plurality of driving ramps including a front ramp, a mid-ramp,and a rear ramp positioned along the shaft of the actuator. The implantmay include an upper ramp connected to the upper endplate assembly andengaged with the plurality of driving ramps. The implant may include alower ramp connected to the lower endplate assembly and engaged with theplurality of driving ramps. The upper and lower endplate assemblies areconfigured to expand in width when the central endplates slide betweenthe outer endplates, and rotation of the actuator and/or the nut maycause independent movement of one or more of the plurality of drivingramps, thereby causing an expansion in height of the upper and lowerendplate assemblies. The inserter instrument may include a cannulaconfigured for deploying the implant into a disc space. The cannula mayinclude a pair of opposed tabs configured to engage the implant to keepthe implant from advancing too far into the disc space. The tabs mayinclude t-shaped tabs configured to mate with corresponding slots in thesides of the implant.

According to yet another embodiment, an expandable implant includes aplurality of upper endplates, a plurality of lower endplates, anactuator assembly, a plurality of driving ramps, and upper and lowerramps. The plurality of upper endplates may include a first plurality oflinks configured to articulate into a generally polygonal shape. Theplurality of lower endplates may include a second plurality of linksconfigured to articulate into the generally polygonal shape. Theactuator assembly may include a rotatable actuator having a shaft. Theplurality of driving ramps may include a front ramp and a rear ramppositioned along the shaft of the actuator. The upper ramp may beconnected to the plurality of upper endplates and engaged with theplurality of driving ramps. The lower ramp may be connected to theplurality of lower endplates and engaged with the plurality of drivingramps. The upper and lower endplates may be configured to expand inwidth. Rotation of the actuator may cause movement of one or more of thedriving ramps, which press against the upper and lower ramps, therebycausing an expansion in height of the upper and lower endplates.

The first and second plurality of links may each include a front linkand a rear link configured to mate with the upper and lower ramps,respectively. The first and second plurality of links may expand inwidth when the rear links move towards the front links. The shaft of theactuator may include a threaded portion and a non-threaded portion. Thefront ramp may be positioned on the non-threaded portion of theactuator, and the rear ramp may be positioned on the threaded portion ofthe actuator. Rotation of the actuator may cause the rear ramp to moveaway from the front ramp, which presses the upper and lower ramps awayfrom one another, thereby expanding the upper and lower endplates inheight.

The upper and lower endplates may be configured to passively pivot abouta longitudinal axis of the implant. For example, the upper and lowerramps may each include a first tab extending outwardly from a proximalend of the ramp and a second tab extending outwardly from a distal endof the respective ramps. The first and second tabs may engage with theendplates, respectively. A portion of the first and second tabs may berounded about a longitudinal axis of the implant, which therebyfacilitates pivotal movement of the endplates about the longitudinalaxis of the implant. In this manner, the upper and lower endplates areable to pivot about the longitudinal axis to passively account for themismatch of the oblique angle of insertion and/or the desired sagittalangle.

According to yet another embodiment, methods of installing theexpandable implants are provided. A disc space of a patient may beaccessed and prepared from a posterior approach. A collapsed implant maybe positioned within the disc space via a cannula from an obliqueapproach. The implant may be expanded in width to a widenedconfiguration. The implant may be expanded in height to an expandedconfiguration. The endplates may passively pivot about a longitudinalaxis of the implant for optimal positioning. The cannula may bewithdrawn from the patient's body, thereby leaving the implant in theexpanded position.

Also provided are kits including expandable fusion devices of varyingtypes and sizes, rods, fasteners or anchors, k-wires, insertion tools,and other components for performing the procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIGS. 1A-1C are lateral, top, and perspective views, respectively, of anexpandable fusion device according to one embodiment, in a fullycollapsed position, shown with a cannula for positioning the expandabledevice on a lower vertebra (the upper adjacent vertebra being omittedfor clarity);

FIGS. 2A-2C show lateral, top, and perspective views, respectively, ofthe expandable fusion device of FIGS. 1A-1C positioned on the lowervertebra (the upper adjacent vertebra being omitted for clarity);

FIGS. 3A-3C show lateral, top, and perspective views, respectively, ofthe expandable fusion device of FIGS. 2A-2C beginning to expand inwidth;

FIGS. 4A-4C show lateral, top, and perspective views, respectively, ofthe expandable fusion device of FIGS. 3A-3C fully expanded in width;

FIGS. 5A-5C show lateral, top, and perspective views, respectively, ofthe expandable fusion device of FIGS. 4A-4C starting to expand inheight;

FIGS. 6A-6C show lateral, top, and perspective views, respectively, ofthe expandable fusion device of FIGS. 5A-5C fully expanded in height;

FIG. 7 shows an exploded view of the expandable fusion device of FIGS.1A-6C;

FIGS. 8A-8C are rear, top, and cross-sectional views, respectively, ofthe expandable fusion device of FIGS. 4A-4C expanded in width andcollapsed in height;

FIGS. 9A-9C are rear, top, and cross-sectional views, respectively, ofthe expandable fusion device of FIGS. 6A-6C expanded in width andexpanded in height;

FIGS. 10A-10D show side, cross-sectional, perspective, and rear views,respectively, of an expandable fusion device according to one embodimentwith a cable or wire for installing the device;

FIGS. 11A-11B show perspective and cross-sectional views, respectively,of an expandable fusion device with a cable or wire according to anotherembodiment;

FIGS. 12A-12C show front perspective views collapsed and expanded inwidth and a top view, respectively, of an expandable fusion deviceaccording to yet another embodiment;

FIG. 13 is an exploded view of an expandable fusion device with aplurality of links according to another embodiment;

FIGS. 14A-14E show rear, perspective, top, side, and front views,respectively, of the expandable fusion device of FIG. 13 in a fullycollapsed position;

FIGS. 15A-15E show rear, perspective, top, side, and front views,respectively, of the expandable fusion device of FIGS. 14A-14E expandedin width and collapsed in height;

FIGS. 16A-16E show rear, perspective, top, side, and front views,respectively, of the expandable fusion device of FIGS. 15A-15E expandedin width and expanded in height;

FIGS. 17A-17C show top and cross-sectional views in collapsed andexpanded configurations, respectively, of the expandable fusion deviceof FIG. 13;

FIGS. 18A-18D show lateral, top, rear, and perspective views,respectively, of the expandable fusion device of FIG. 13 implanted in adisc space;

FIG. 19A-19D show rear, perspective, top, and side views, respectively,of an expandable fusion device according to another embodiment; and

FIGS. 20A-20D show lateral, top, rear, and perspective views,respectively, of the expandable fusion device of FIGS. 19A-19D implantedin a disc space.

DETAILED DESCRIPTION OF THE INVENTION

In order to improve the access profile of the interbody while maximizingcortical bone contact surface area, the interbody implant may bepositioned within the disc space with a narrow profile that expands inwidth to increase surface area contact. The implant may be configured toexpand in height to restore anatomical spinal alignment. While expandingin height, the anterior and/or posterior heights of the implant may beindividually adjusted, for example, to adjust sagittal balancecorrection. Accordingly, embodiments of the present application aregenerally directed to devices, systems, instruments, and methods forinstalling, and expanding the interbody implant in width and/or height.The terms implant, interbody, interbody implant, fusion device, spacer,and expandable device may be used interchangeably herein.

Referring now to FIGS. 1A-9, an expandable interbody fusion device orimplant 20 and method of installation according to one embodiment isshown. The expandable device 20 is configured to expand in both widthand height. The implant 20 is configured to be inserted in a collapsedorientation, which defines its smallest dimensions in both width andheight. Once inserted into the disc space, the implant 20 is actuated tohave an increased width, thereby providing an expanded footprint thatfully maximizes surface contact area with the vertebral body 2. Theimplant 20 is then expanded in height to an expanded orientation toprecisely restore normal spinal alignment and evenly distribute the loadacross the vertebral endplates 4.

The implant 20 extends from a rear end or proximal end 22 configured toconnect with an insertion instrument to a nose end or distal end 24configured to be inserted first into the disc space. The implant 20includes a plurality of upper endplates 26 and a plurality of lowerendplates 28, which are configured to engage with the adjacent vertebrae2. The plurality of upper endplates 26 may include a first upper outerendplate 30, a second upper outer endplate 32, and a third upper centralendplate 34 positionable between the first and second upper outerendplates 30, 32. Similarly, the plurality of lower endplates 28 mayinclude a first lower outer endplate 36, a second lower outer endplate38, and a third lower central endplate 40 positionable between the firstand second lower outer endplates 36, 38. The central endplates 34, 40are configured to expand the respective outer endplates 30, 32, 36, 38outwardly, thereby expanding the overall width of the implant 20.

With emphasis on FIGS. 1A-1C, the expandable fusion device or implant 20is shown with a guide tube or cannula 10 for deployment of the device 20into a disc space between adjacent vertebral bodies 2 (the uppervertebra is omitted for clarity). The cannula 10 may be suitable for useduring a minimally invasive surgical (MIS) procedure, for example. Theguide tube or cannula 10 extends from a proximal end 12 to a distal end14 positionable within the disc space. The cannula 10 defines a centrallongitudinal opening 16 configured to guide the implant 20 into the discspace. The disc space may be accessed through a posterior approach. Thecannula 10 may be docked on the disc space through Kambin's triangle, orthe anatomical area that is bordered by the disc space, exiting nerveroot, and traversing nerve root. For example, as shown, the cannula 10may be angled relative to the vertebra 2. For example, the cannula maybe angled about 30° relative to a straight posterior access approach.

Turning now to FIGS. 2A-2C, the implant 20 is inserted into the discspace in a fully collapsed orientation, which is collapsed in both widthand height, through the cannula 10 to its final position. The wideningexpansion will be described with reference to the upper endplates 26. Itwill be appreciated that the lower endplates 28 expand in the samemanner. In the collapsed orientation, the outer endplates 30, 32 arenested together. The outer endplates 30, 32 may be positioned in contactor close to one another. As the implant 20 reaches its final position,one or more tabs 18 on the cannula 10 engage the implant 20 to keep itfrom advancing further into the disc space. The tabs 18 may include apair of opposed tabs 18, for example, provided on opposite sides of theimplant 20. In one embodiment, the tabs 18 include t-shaped tabsconfigured to mate with corresponding slots in the sides of the implant20. The t-shaped tab 18 may have a narrow body and an enlarged free end,thereby defining a substantially t-shaped member extending distally fromthe distal end 14 of the cannula 10. Although t-shaped tabs 18 areexemplified in this embodiment, it will be appreciated that the tabs 18may be otherwise shaped or configured to engage and retain the implant20.

Turning now to FIGS. 3A-3C, the implant 20 is beginning to expand inwidth. The central wedge endplate 34 is configured to move the outerendplates 30, 32 outwardly. As the outer endplates 30, 32 begin toexpand away from one another, a gap 42 is formed between the outerendplates 30, 32. The central endplate 34 has a nose portion 44. Thenose portion 42 may be angled, tapered, or pointed to facilitateinsertion between the outer endplates 30, 32. As the nose portion 44 ismoved forward distally and into the gap 42 the outer endplates 30, 32continue to widen outwardly. The central endplate 34 may be configuredto slide between the outer endplates 30, 32 on one or more tracks 46.The track or tracks 46 may include one or more corresponding channelsand rails, for example. As the central endplate 34 continues to advanceforward distally along the tracks 46, the outer endplates 30, 32 expandin width. The central endplate 34 wedges out the expanding footprintendplates 30, 32. The second outer endplate 32 may include an elongategroove 48 and the first outer endplate 30 may retain a pin 50 configuredto be received within the elongate groove 48. As the outer endplates 30,32 move outwardly, the pin 50 is guided along the path of the groove 48.For example, a linear groove 48 shown in this embodiment provides for agenerally parallel expansion in width of the first and second outerendplates 30, 32. It will be appreciated that the groove 48 could beangled, curved, or otherwise configured to provide for the desired typeof expansion in width.

With further emphasis on FIGS. 4A-4C, the implant 20 is shown fullyexpanded in width. The nose 44 of the central endplate 34 moves forwarddistally, and the central endplate 34 substantially fills the gap 42between the outer endplates 30, 32. The central endplate 34 is fullyadvanced to engage the front of the expanding footprint endplates 30,32. The expanded footprint fully maximizes surface contact area of theendplate 26 with the vertebral body 2. Once in the widened orientationshown, the implant 20 is ready to be expanded in height.

Turning now to FIGS. 5A-5C, the implant 20 is beginning to expand inheight. As the implant 20 is expanded, the implant 20 may independentlyadjust the anterior and/or posterior aspects of the implant 20 tocontrol sagittal balance. When each endplate 26, 28 comes in contactwith the vertebral endplates 4, the upper and lower endplates 26, 28 maybe configured to passively pivot to maximize the force distributionacross the vertebral endplates 4. With further emphasis on FIGS. 6A-6C,the implant 20 is expanded in height and width. The implant 20 maycontinue to be expanded to adjust correction and sagittal balance andthe passive joint may continue to adjust as needed.

With emphasis on FIG. 7, an exploded view of the implant 20 is shown.The implant 20 includes a first assembly or first plurality of upperendplates 26 and a second assembly or second plurality of lowerendplates 28 configured to engage adjacent vertebrae 2. The implant 20includes an actuation mechanism including an actuator 52 and a nut 54configured to move a plurality of internal ramps 56, which expand theendplate assemblies 26, 28 in height. The plurality of ramps 56 mayinclude a plurality of driving ramps including a front ramp 58, amid-ramp 60, and a rear ramp 62. The front ramp 58 may include a centrallongitudinal bore 59, the mid-ramp 60 may include a central longitudinalbore 61, and the rear ramp 62 may include a central longitudinal bore63. The plurality of driving ramps 58, 60, 62 may be positioned alongthe length of the actuator 52 and are configured to engage and drive anupper ramp 64 and a lower ramp 66, respectively. The upper and lowerramps 64, 66 are connected to the upper and lower endplate assemblies26, 28. When one or more of the driving ramps 58, 60, 62 are moved andslide against the upper and lower ramps 64, 66, thereby providing forexpansion of the implant 20 in height. The expansion may include theability to individually adjust the anterior and/or posterior heights ofthe implant 20.

The upper endplate assembly 26 may include first and second upper outerendplates 30, 32 and central wedge endplate 34 slidable between theupper outer endplates 30, 32 to expand the upper outer endplates 30, 32in width. The lower endplate assembly 28 may include the first andsecond lower outer endplates 36, 38 and central wedge endplate 40slidable between the lower outer endplates 36, 38 to expand the lowerouter endplates 36, 38 in width. It will be appreciated that the lowerendplates 28 are identical to the upper endplates 26 and the descriptionfor the upper endplates 26 provided herein applies equally to the lowerendplates 28. One or more of the endplates 30, 32, 34 may include aplurality of teeth 68, protrusions, or other friction enhancing surfacesconfigured to engage bone. The central endplate 34 may include a largecentral graft retaining opening or window 70 and the outer endplates 30,32 may include one or more graft openings or windows 72 configured toreceive bone graft or other suitable bone growth enhancing material.

The nose end or distal end 24 of the first outer endplate 30 may includea first projection 74 extending inwardly toward the second outerendplate 32. Similarly, the distal end of the second outer endplate 32may include a second projection 76 extending inwardly toward the firstouter endplate 30. The projection 76 may define elongate groove oropening 48 extending generally perpendicular to the longitudinal axis Aof the implant 20. The projection 74 may include an opening 78 forreceiving a pin 50 therein. The pin 50 is configured to slide along theelongate opening 48, thereby facilitating expansion of the width of theouter endplates 30, 32. It will be appreciated that the locations of thepin 50 and groove 48 may be reversed in the outer endplates 30, 32.

The rear end or proximal end 22 of the first outer endplate 30 mayinclude an angled portion 80 and the proximal end of the second outerendplate 32 may include a second angled portion 82. The angled portions80, 82 may be configured to receive the nose portion 44 of the centralendplate 34 when the implant 20 is in the fully collapsed position. Theinner surfaces of the outer endplates 30, 32 define one or more tracks46 configured to engage corresponding tracks 46 positioned along thesides of the central endplate 34. The tracks 46 along the nose 44 of thecentral endplate 34 mate with the corresponding tracks 46 along theangled portions 80, 82 of the outer endplates 30, 32, respectively. Asthe central endplate 34 is advanced forward to expand the width, thetracks 46 along the edges of the central endplate 34 mate with thecorresponding tracks 46 along the inner surfaces of the outer endplates30, 32. The tracks 46 may include male and female grooves andprojections configured to mate with a slidable interface. For example,the tracks 46 may include one or more female channels and one or moremale rails enabling the central endplate 34 to slide between the outerendplates 30, 32 and extend them outwardly to widen the footprint of theimplant 20.

The implant 20 includes an actuation assembly configured to expand theheight of the implant 20. The actuation assembly includes a rotatableactuator 52 and rotatable nut 54 configured to move a plurality ofinternal ramps 56. The implant 20 includes at least three driving ramps,front ramp 58, mid-ramp 60, and rear ramp 62, which interface with theactuator 52. The actuator 52 may include a shaft 84 extending from aproximal end 86 to a distal end 88. The shaft 84 includes a firstthreaded portion 90, a second threaded portion 92, and a non-threadedportion 94. The first and second threaded portions 90, 92 may havedifferent attributes including outer diameters, handedness, thread form,thread angle, lead, pitch, etc.

In FIGS. 8A-8C, the implant 20 is shown in a widened orientation andcollapsed in height and in FIGS. 9A-9C, the implant 20 is shown in awidened orientation and expanded in height. As best seen in FIG. 9C, thefront driving ramp 58 is positioned on the non-threaded portion 94 ofthe actuator 52. The front driving ramp 58 may be located between asecuring washer 96 and a shoulder 98 defined between the first threadedportion 90 and the non-threaded portion 94. In this manner, the frontramp 58 is secured to the actuator shaft 84. In an alternativeembodiment, the front ramp 58 may be positioned along another threadedportion in order to move the front ramp 58 along the actuator shaft 84.The mid-ramp 60 is positioned on the first threaded portion 90 and ismoveable along the length of the first threaded portion 90 in order tomove the mid-ramp 60 and thereby move the upper and lower ramps 64, 66to expand the implant 20. The rear ramp 62 is positioned along thesecond threaded portion 92 in order to move the rear ramp 62. The rearramp 62 is moveable along the length of the second threaded portion 92to move the upper and lower ramps 64, 66 and expand the implant 20. Thefirst threaded portion 90 may have a smaller outer diameter anddifferent handedness than the second threaded portion 92. The firstthreaded portion 90 may transition to the second threaded portion 92 ata second shoulder 100. The proximal end 86 of the actuator shaft 84 mayinclude a first instrument retention feature, such as a ribbed neck 102.The ribbed neck 102 may include knurled neck grips or other suitableengagement surfaces, which are configured to interface with a driverinstrument to thereby rotate the actuator shaft 84.

The actuation assembly may also include a rotatable nut 54. Therotatable nut 54 may be configured to move the rear ramp 62 independentof the mid-ramp 60 and front ramp 58. The nut 54 may extend from aproximal end 104 to a distal end 106. The distal end 106 may include anouter threaded portion 108 configured to mate with a correspondinginternal threaded portion in the bore 63 through the rear driving ramp62. The proximal end 104 may include a second instrument retentionfeature, such as a slotted head 110. The slotted head 110 may includeslots or other suitable engagement surfaces configured to interface witha driver instrument to thereby rotate the nut 54. When only the nut 54is rotated clockwise, the rear ramp 62 is translated forward, decreasingit's distance to the front ramp 58 and the posterior height increasesand the anterior height decreases thus decreasing the lordotic angle ofthe spacer. When the nut 54 remains stationary and only the actuator 52is rotated clockwise, the mid ramp 60 moves away from the front ramp 58increasing the anterior height, at the same time the rear ramp 62 movesaway relative to the front ramp 58 as the actuator 52 advances throughthe nut 54. Increasing the gap between the rear ramp 62 and the frontramp 58 increases the lordotic angle of the spacer. When both theactuator 52 and the nut 54 are rotated clockwise at the same time, therear ramp 62 and the front ramp 58 do not move relative to each other.Only the mid ramp 60 translates away from the front ramp 58 and towardsthe rear ramp 62. This results in parallel expansion of the theendplates 26, 28. It will be appreciated that the movement of thedriving ramps 58, 60, 62 and resulting expansion may be operated by theactuator 52 and/or nut 54 with any suitable configurations andmechanisms.

The driving ramps 58, 60, 62 engage with upper ramp 64 and lower ramp 66to thereby move the upper and lower ramps 64 outwardly in height. Itwill be appreciated that the lower ramp 66 is identical to the upperramp 64 and the description for the upper ramp 64 herein applies equallyto the lower ramp 66. The upper ramp 64 extends from a proximal end 112to a distal end 114. The upper ramp 64 includes an outer surface 116configured to be received within a cavity 118 in the central ramp 34. Aportion of the outer surface 116 may be rounded about the longitudinalaxis A of the implant 20 to facilitate movement of the endplates 26about the longitudinal axis A of the implant 20. The outer surface 116of the upper ramp 64 may define one or more recesses or slots 142configured to guide one or more corresponding tabs 144 on the innercavity 118 of the central endplate 34. The slot 142 may include acircular t-slot configured to guide or pivot the central endplate 34about the longitudinal axis A of the implant 20. In this manner, theupper endplate assembly 26 is configured to passively pivot about thelongitudinal axis A to account for lordosis and/or the oblique deliveryangle of insertion. Without this type of polyaxial joint, the endplates26, 28 could dig into and/or tip the vertebral bodies 2 when implanted.

The upper ramp 64 includes an inner surface 120 configured to mate withthe driving ramps 58, 60, 62. The inner surface 120 may include one ormore ramped surfaces 122, 124, 126. In the embodiment shown, the innersurface 120 includes a first ramped surface 122 near the proximal end112 of the ramp 64, a second ramped surface 124 near the distal end 114of the ramp 64, and a third ramped surface 126 between the first andsecond ramped surfaces 122, 124. The first ramped surface 122 may facethe proximal end 112, the second ramped surface 124 may face theproximal end 112, and the third ramped surface 124 may face the distalend 114. The ramped surfaces 122, 124, 126 may be angled continuoussurfaces with a given angle of slope. It is contemplated that the slopeof the ramped surfaces 122, 124, 126 may be equal or can differ fromeach other. The ramped surfaces 122, 124, 126 may be generally straightramped surfaces or may be curved ramped surfaces. The ramped surfaces122, 124, 126 may include male slide ramps or protruding ramps. Thefirst and second ramped surfaces 122, 124 may be spaced apart at anequal distance such that the ramped surfaces 122, 124 are substantiallyparallel to one another. The third ramped surface 126 may be angledopposite to the first and second ramped surfaces 122, 124. In this waythe apex of the third ramp 126 may meet or near the apex of the firstramp 122 and the base of the third ramp 126 may meet or near the base ofthe second ramp 124. Although a specific arrangement of ramped surfaces122, 124, 126 is shown, it is envisioned that the number, location, andconfiguration of ramped surfaces 122, 124, 126 may be modified orselected by one skilled in the art.

The driving ramps 58, 60, 62 may include one or more ramped surfaces128, 130, 132. The ramped surfaces 128, 130, 132 of the driving ramps58, 60, 62 may be configured and dimensioned to engage the correspondingramped surfaces 122, 124, 126 of the upper and lower ramps 64, 66,respectively. For example, the rear ramp 62 may include one or moreramped surfaces 128, mid-ramp 60 may include one or more ramped surfaces130, and front ramp 58 may include one or more ramped surfaces 132. Theramped surfaces 128, 130, 132 may be angled continuous surfaces with agiven angle of slope. It is contemplated that the slope of the rampedsurfaces 128, 130, 132 may be equal or can differ from each other. Theramped surfaces 128, 130, 132 may be generally straight ramped surfacesor may be curved ramped surfaces. The ramped surfaces 128, 130, 132 mayinclude female slide ramps or recessed ramps configured to receive themale ramped surfaces 122, 124, 126 of the upper ramp 34. It will beappreciated that the male and female ramps may be reversed or may beotherwise configured to provide for slidable mating between the ramps.The first ramped surface 122 of the upper ramp 34 may be configured toslidably interface with the ramped surface 128 of the driving rear ramp62. The second ramped surface 124 of the upper ramp 34 may be configuredto slidably interface with the ramped surface 132 of the driving frontramp 58. The third ramped surface 126 of the upper ramp 34 may beconfigured to slidably interface with the ramped surface 130 of thedriving mid-ramp 60. As one or more of the driving ramp 58, 60, 62moves, the ramped surface or surfaces 128, 130, 132 pushes against thecorresponding ramped surface or surfaces 122, 124, 126 of the upper andlower ramps 64, 66. In this manner, the individual driving ramps 128,130, 132 control the rate of expansion of the upper and lower ramps 64,66, which thereby controls the expansion of the attached upper and lowerendplates 26, 28. The upper and lower endplate assemblies 26, 28 arepushed outwardly into the expanded configuration.

The implant 20 may further include one or more of the followingfeatures. The driving rear ramp 62 may include an outer threaded portion134 at the proximal end which may be configured to be retained by aninsertion instrument. One or more friction rings or washers 136 may beprovided to provide drag or thrust resistance to the nut 54 and/ordriving ramps 58, 60, 62, respectively. A locking member 138 may beprovided to capture and secure the nut 54 in the assembly. One or morepins 140 may be provided to limit travel and keep the endplates 26connected together.

In order to improve the access profile of the interbody implant 20 whilemaximizing cortical bone contact surface area, methods and systems ofinstalling, widening, and/or expanding the implant 20 may include one ormore of the following. The implant 20 may enter the disc space with anarrow profile and articulate to increase surface area contact on theanterior apophyseal ring. The orientation and position of the interbodyimplant 20 in its final implanted position may be optimized bypre-/intra-op scans and/or normal population statistics that determinebone mineral density maps of the vertebral body. Robotic and/ornavigation guidance may be used to correctly orient the interbody 20.Further details of robotic and/or navigational systems can be found inU.S. Patent Publication No. 2017/0239007, which is incorporated hereinby reference in its entirety for all purposes.

In one embodiment, the implant 20 may be implanted with one or more ofthe following steps: (1) A determination is made on final optimalimplant location to optimize bone mineral density of the contactedbone/implant interface. (2) Robotic and/or navigation is used todetermine the potential trajectories that will allow for this optimalimplant location to be achieved. (3) The cannula 10 is docked on thedisc space through Kambin's triangle, or the anatomical area that isbordered by the disc space, exiting nerve root, and traversing nerveroot. (4) The expandable interbody 20 is inserted in thenon-articulated, non-expanded orientation. (5) The expandable interbody20 is actuated into the expanded or widened footprint that fullymaximizes surface contact area with the vertebral body. (6) Theexpandable interbody 20 is then expanded in height to precisely restorenormal spinal alignment and evenly distribute the load across thevertebral endplates 4.

Turning now to FIGS. 10A-10D, an expandable interbody fusion device orimplant 150 according to another embodiment is shown. Implant 150expands in width similar to implant 20 with a central wedge endplate164. In this embodiment, the cannula 10 is replaced with one or morecables or wires 196, which is connected to each endplate to hold them inposition while advancing the central wedge endplate 164 forward to widenthe footprint of the implant 150. The cable or wire 196 may be loopedthrough the endplate assemblies 156, 158 and out to the back of theinstrumentation for holding.

The implant 150 extends from a rear end or proximal end 152 configuredto connect with an insertion instrument to a nose end or distal end 154configured to be inserted first into the disc space. The implant 150includes a first assembly or first plurality of upper endplates 156 anda second assembly or second plurality of lower endplates 158 configuredto engage adjacent vertebrae 2. The upper endplate assembly 156 mayinclude first and second upper outer endplates 160, 162 and the lowerendplate assembly 158 may include first and second lower outer endplates166, 168. The central wedge endplate 164 is slidable between the outerendplates 160, 162, 166, 168 to thereby expand the outer endplates 160,162, 166, 168 in width. The central endplate 164 may include one or moregraft retaining openings or windows 170 configured to receive bone graftor other suitable bone growth enhancing material.

The distal end 154 of the implant 150 may include a nose assembly 172including an upper nose portion 174, a lower nose portion 176, and acentral nose portion 178 positioned between the upper and lower noseportions 174, 176. The upper and lower endplates 156, 158 connect to thenose assembly 172 with one or more pivotable linking members or links180. The distal end of the first upper endplate 160 connects to one ofend of a first linking member 180 with a first pivot pin 182 and theopposite end of the linking member 180 connects to the upper nose 174with a second pivot pin 182. Similarly, the distal end of the secondupper endplate 162 connects to one of end of a second linking member 180with a third pivot pin 182 and the opposite end of the linking member180 connects to the upper nose 174 with a fourth pivot pin 182. Thelower endplates 158 are connected to the lower nose portion 176 withadditional links 180 and pivot pins 182 in the same manner.

The proximal ends of the outer endplates 156, 158 may each include anangled portion 184 configured to receive the nose portion 186 of thecentral endplate 164 when the implant 150 is in the fully collapsedposition. The inner surfaces of the outer endplates 156, 158 may defineone or more tracks 188 configured to engage corresponding tracks 188positioned along the sides of the central endplate 164. The tracks 188along the nose 186 of the central endplate 164 mate with thecorresponding tracks 188 along the angled portions 184 of the outerendplates 156, 158, respectively. As the central endplate 164 isadvanced forward to expand the width, the tracks 188 along the edges ofthe central endplate 164 mate with the corresponding tracks 188 alongthe inner surfaces of the outer endplates 160, 162. The tracks 188 mayinclude male and female grooves and projections configured to mate witha slidable interface. For example, the tracks 188 may include one ormore female channels and one or more corresponding male rails enablingthe central endplate 164 to slide between the outer endplates 156, 158and extend them outwardly to widen the footprint of the implant 150. Oneor more of the tracks 188 may form a slidable dovetail configuration.

The proximal end 152 of the implant 150 includes a rear assembly 190 forsecuring one or more cables or wires 196. The rear assembly 190 mayinclude a ring 192 and a base 194 positioned between the ring 192 andthe slidable central endplate 164. The rear assembly 190 may beconfigured for attachment to an insertion instrument, for example. Thecable or wire 196 may be looped through the endplate assemblies 156, 158and out to the back of the instrumentation for holding. The wire 196 maybe secured to the ring 192 at the proximal end 152 of the implant 150and loop around the implant 150. For example, as best seen in FIG. 10B,the wire 196 may connect to the ring 192 at a first location, extendalong a first side of the central wedge endplate 164, bend inwardlyfollowing the nose 186 of the central wedge endplate 164, travel alongan inner surface of the outer endplates 156, 158, pinch inwardly nearthe links 180, loop around the central nose 178 of the nose assembly172, pinch inwardly near the links 180, travel along an inner surface ofthe outer endplates 156, 158, bend outwardly following the nose 186 ofthe central wedge endplate 164, extend along a second side of thecentral wedge endplate 164 and reconnect to the ring 192 at a secondlocation opposite to the first location. The wire 196 may be recessedinto a central male track 188 extending along the side of the centralwedge endplate 164. The cable or wire 196 may be configured for holdingthe implant 150 during the widening expansion.

Turning now to FIGS. 11A-11B, an expandable interbody fusion device orimplant 200 according to another embodiment is shown. Implant 200 issimilar to implant 150 except the cable or wire 196 extends centrallythrough the implant 200. The wire 196 may connect to the nose assembly202 to hold each of the outer endplates 156, 158 in position whileadvancing the central endplate 164 forward. The wire 196 may connect tothe back of the instrumentation for holding. In this embodiment, thenose assembly 202 includes an upper nose 204 connected to a lower nose206 and the rear assembly 208 includes a pin 210 and a base 212. A firstend of the cable or wire 196 anchors into the upper and lower noseportions 204, 206 at the distal end 154 and the second end of the wire196 attaches to the pin 210 at the proximal end 152. The wire 196 mayextend along the central longitudinal axis of the implant 200 from thenose assembly 202, through the central wedge endplate 164, through thebase 212, and transversely into the pin 210. The central wedge endplate164 may slide along the wire 196 and as the central endplate 164 movesforward, the central endplate 164 expands the outer endplates 156, 158in the same manner as described herein for implant 150.

Turning now to FIGS. 12A-12C, an expandable interbody fusion device orimplant 220 according to another embodiment is shown. Implant 220 issimilar to implants 150, 200 except the nose is replaced with a pinassembly 222. The pin assembly 222 may include one or more elongate pins224, a first collar 226 surrounding and rotatable about the pin 224, anda second collar 228 surrounding and rotatable about the pin 224. Theelongate pin 224 may extend from an upper surface of the upper endplates156 to a lower surface of the lower endplates 158. The first collar 226may connect to the upper links 180 rotatably coupled to the upperendplates 156 and the second collar 228 may connect to the lower links180 rotatably coupled to the lower endplates 158. In the collapsedposition shown in FIG. 12A, the links 180 pivot inwardly, therebyallowing the outer endplates 156, 158 to contact or be positioned nearone another to provide a minimum width for the implant 200. As thecentral wedge endplate 164 is advanced forward toward the distal end154, the tracks 188 of the central wedge endplate 164 slide along themating tracks 188 along the inner surfaces of the outer endplates 160,162, 164, 168. In this embodiment, the tracks 188 along the centralwedge endplate 164 include a male upper track 188, a lower male track188, and a central male track 188 positioned between the upper and lowermale tracks 188. The male tracks 188 are separated by elongate grooves.The pin assembly 222 and the pin 182 connecting the links 180 to therespective endplates 160, 162, 164, 168 allow the endplates 160, 162,164, 168 to expand in width when the central endplate 164 slides alongthe mating tracks 188. As the links 180 pivot outwardly, the outerendplates 156, 158 move away from one another to provide a maximum widthfor the implant 200.

Referring now to FIGS. 13-18D, an expandable interbody fusion device orimplant 230 and method of installation according to one embodiment isshown. The expandable device 230 is configured to expand in both widthand height. The implant 230 is configured to be inserted in a collapsedorientation, which defines its smallest dimensions in both width andheight. Once inserted into the disc space, the implant 230 is actuatedto have an increased width, thereby providing an expanded footprint thatfully maximizes surface contact area with the vertebral body 2. Theimplant 230 is then expanded in height to an expanded orientation toprecisely restore normal spinal alignment and evenly distribute the loadacross the vertebral endplates 4.

In FIG. 13, an exploded view of the implant 230 is shown. FIGS. 14A-14Eshow the implant 230 in the collapsed configuration, minimized in bothwidth and height. FIGS. 15A-15E show the implant 230 in a widenedconfiguration with the implant 230 increased in width. FIGS. 16A-16Eshow the implant 230 in an expanded configuration with the implant 230increased in width and height. The implant 230 extends from a rear endor proximal end 232 configured to connect with an insertion instrumentto a nose end or distal end 234 configured to be inserted first into thedisc space. The implant 230 includes a first assembly or first pluralityof upper endplates 236 and second assembly or second plurality of lowerendplates 238, which are configured to engage with the adjacentvertebrae 2. When articulated to the widened footprint, the implant 230may define one or more central windows or openings 240 extending betweenthe upper and lower endplates 236, 238. The central window or opening240 may be configured to receive bone graft or a bone growth inducingmaterial. The bone graft can be introduced within and/or around thefusion device 230 to further promote and facilitate the intervertebralfusion.

The upper and lower endplates 236, 238 may each include a plurality ofindividual linking segments or links 242. It will be appreciated thatthe lower endplate assembly 238 is identical to the upper endplateassembly 236 and the description for the upper endplates 236 providedherein applies equally to the lower endplates 238. The plurality oflinking segments or links 242 may be configured to articulate into agenerally polygonal shape. The polygon may be convex, concave, simple,intersecting, or of other suitable type. The shape of the polygon may bedictated by the number of segments or links 242 used to build theimplant 230. For example, a device 230 with eight links 20, as shown inthis embodiment, may form an octagon. Although the device 230 is shownwith eight links 242 for each of the upper and lower endplates 236, 238forming a generally octagonal shape, it is envisioned that the device230 may have as few links 242 or as many as desired. The links 242 mayhave the same length or the links 242 may be of different lengths. Inthe embodiment shown, the rear-most link 243 and front-most link 245have a shorter length than the remaining side links 242, and each of theside links 242 have the same length. It will be appreciated that thelinks 242 may be of any suitable length.

Each of the links 242 are connected and able to articulate about a pivotjoint 244. The pivot joint 244 may be a revolute joint such as a pinjoint or hinge joint. For example, the pivot joint 244 may provide auni-axial rotation or single-axis rotation about one or more pins 246,for example. The connected links 242 may be able to rotate freely aboutthe axis of each respective pin 246 between connected links 242.Although pins 246 are exemplified herein, it will be appreciated thatother joint geometries may be used. The implant 230 is inserted in itscollapsed position shown in FIGS. 14A-14E. Once inserted, the implant230 is widened by applying a force to the rear-most link 243, therebymoving the rear-most link 243 forward toward the front-most link 245. Asthe rear-most link 243 moves forward toward the distal end 234, thelinks 242 along the sides of the implant 230 pivot outwardly into thewidened configuration shown in FIGS. 15A-15E.

The implant 230 includes an actuator assembly including an actuator 248configured to move a plurality of internal ramps 250, which expand theendplate assemblies 236, 238 in height. The plurality of ramps 250 mayinclude a front driving ramp 252 and a rear driving ramp 254. The frontdriving ramp 252 may include a central longitudinal bore 253 and therear driving ramp 254 may include a central longitudinal bore 255. Theplurality of driving ramps 252, 254 may be positioned along the lengthof the actuator 248 and are configured to engage and drive an upper ramp256 and a lower ramp 258, respectively. The upper and lower ramps 256,258 are engaged with the upper and lower endplate assemblies 26, 28,thereby providing for expansion of the implant 230 in height.

The actuator 248 may include a shaft 260 extending from a proximal end262 to a distal end 264. The shaft 260 may include a threaded portion266 and a non-threaded portion 268. In FIG. 17B, a cross-sectional viewof the implant 230 is shown along line A-A from FIG. 17A in a widenedorientation and collapsed in height. In FIG. 17C, a cross-sectional viewof the implant 230 is shown along line A-A in a widened orientation andexpanded in height. As best seen in FIG. 17C, the front driving ramp 252is positioned on the non-threaded portion 268 of the actuator 248. Thefront driving ramp 252 may be located between a securing washer 270 anda shoulder 272 along the non-threaded portion 268. In this manner, thefront driving ramp 252 is secured to the actuator shaft 248. The reardriving ramp 254 is positioned along the threaded portion 266 of theshaft 260 in order to move the rear ramp 254 when the shaft 260 isrotated. The rear ramp 254 is moveable along the length of the threadedportion 266 to move the upper and lower ramps 256, 258 and expand theimplant 230. For example, as shown in FIG. 17B, the rear ramp 254 ispositioned near a distal end of the threaded portion 266. As the implant230 is expanded, as shown in FIG. 17C, the rear ramp 254 moves toward aproximal end of the threaded portion 266. As the actuator 248 movesforward, front ramp 252 may move forward and rear ramp 254 may movebackward, thereby moving away from the front ramp 252, and expanding theimplant 230 in height. The proximal end 262 of the actuator shaft 260may include an instrument retention feature, such as a ribbed neck 274.The ribbed neck 274 may include knurled neck grips or other suitableengagement surfaces, which are configured to interface with a driverinstrument to thereby rotate the actuator shaft 260.

The driving ramps 252, 254 engage with upper ramp 256 and lower ramp 258to thereby move the upper and lower ramps 256, 258 outwardly in height.It will be appreciated that the lower ramp 258 is identical to the upperramp 256 and the description for the upper ramp 256 herein appliesequally to the lower ramp 258. The upper ramp 256 extends from aproximal end 276 to a distal end 278, which are configured to engagewith the upper endplates 236. In particular, a first tab 280 may extendoutwardly from the proximal end 276 of the ramp 256 and a second tab 282may extend in the opposite direction outwardly from the distal end 278of the ramp 256. A portion of the first and second tabs 280, 282 may berounded about the longitudinal axis A of the implant 230. For example, arounded portion 283 on the upper ramp 256 may include an upper surfaceconfigured to mate with the upper endplates 236 and the rounded portion283 on the lower ramp 258 may include a lower surface configured to matewith the lower endplates 238. The rounded portions 283 may facilitatemovement of the endplates 236 about the longitudinal axis A of theimplant 230. The rounded portion 283 may be received in a mating roundedrecess 294 defined within the rear-most link 243. A similar roundedmating interface may be provided within the opening 247 in thefront-most link 245. In this manner, the upper endplate assembly 236 isconfigured to pivot about the longitudinal axis A so that the implant230 can passively account for the mismatch of the oblique angle ofinsertion and the desired sagittal angle. Without this type of polyaxialjoint, the endplates 236, 238 could dig into and/or tip the vertebralbodies 2 when implanted.

The upper ramp 256 includes an inner surface 284 configured to mate withthe driving ramps 252, 254. The inner surface 284 may include one ormore ramped surfaces 286, 288. In the embodiment shown, the innersurface 284 includes at least a first ramped surface 286 near theproximal end 276 of the upper ramp 256 and at least a second rampedsurface 288 near the distal end 278 of the upper ramp 256. The firstramped surface 286 may include a first pair of ramped surfaces 286 andthe second ramped surface 288 may include a second pair of rampedsurfaces 288. The ramped surfaces 286, 288 may be angled continuoussurfaces with a given angle of slope. The ramped surfaces 286, 288 mayinclude male slide ramps or protruding ramps. The first and secondramped surfaces 286, 288 may be angled opposite to one another such thatthe ramped surfaces 286, 288 may face one another. For example, thefirst ramped surface 286 may have an apex near the proximal end 276 andthe second ramped surface 288 may have an apex near the distal end 278of the ramp 256. Although a specific arrangement of ramped surfaces 286,288 is shown, it is envisioned that the number, location, andconfiguration of ramped surfaces 286, 288 may be modified or selected byone skilled in the art.

The driving ramps 252, 254 include one or more ramped surfaces 290, 292configured to mate with the corresponding ramped surfaces 286, 288 ofthe upper and lower ramps 256, 258. For example, the rear driving ramp254 may include one or more ramped surfaces 290 and front driving ramp252 may include one or more ramped surfaces 292. The ramped surfaces290, 292 may be angled continuous surfaces with a given angle of slope.The ramped surfaces 290, 292 may include female slide ramps or recessedramps configured to receive the male ramped surfaces 286, 288 of theupper and lower ramps 256, 258. It will be appreciated that the male andfemale ramps may be reversed or may be otherwise configured to providefor slidable mating between the ramps. The first ramped surface 286 ofthe upper ramp 256 may be configured to slidably interface with theramped surface 290 of the rear driving ramp 254. The second rampedsurface 288 of the upper ramp 256 may be configured to slidablyinterface with the ramped surface 292 of the front driving ramp 252. Inthis manner, the individual driving ramps 252, 254 control the rate ofexpansion of the upper and lower ramps 256, 258, which thereby controlsthe expansion of the attached upper and lower endplate assemblies 236,238.

As shown in FIGS. 18A-18C, implant 230 may be implanted from an obliqueapproach similar to implant 20. The spine may be accessed posteriorly. Acannula may be docked on the disc space through Kambin's triangle, orthe anatomical area that is bordered by the disc space, exiting nerveroot, and traversing nerve root. The approach may be oblique, forexample, at about a 30° angle relative to a straight posterior accesspath. The expandable interbody 230 is inserted in the non-articulated,collapsed orientation. The expandable interbody 230 is actuated into theexpanded footprint that fully maximizes surface contact area with thevertebral body 2. Then, the expandable interbody 230 is expanded inheight to precisely restore normal spinal alignment and evenlydistribute the load across the vertebral endplates. The passivelongitudinal axis allows for the implant endplates 236, 238 to pivot tomatch the vertebral body endplate angles and minimize any edge loading.

Turning now to FIGS. 19A-20D, an expandable interbody fusion device orimplant 300 according to another embodiment is shown. The expandabledevice 300 is similar to implant 230 but is only configured to expand inheight. The implant 300 is configured to be inserted in a collapsedorientation, which defines its smallest height. Once inserted into thedisc space, the implant 300 is expanded in height to an expandedorientation. Similar to implant 230, the implant 300 may be configuredto pivot about the longitudinal axis A of the implant 300 so that it canpassively account for the mismatch of the oblique angle of insertionand/or the desired sagittal angle.

As best seen in FIGS. 19A-19D, the implant 300 extends from a rear endor proximal end 302 configured to connect with an insertion instrumentto a nose end or distal end 304 configured to be inserted first into thedisc space. The proximal end 302 of the implant 300 may include an outerthreaded portion 310 configured to threadedly mate with an insertioninstrument.

The implant 300 includes a first or upper endplate 306 and a second orlower endplate 308, which are configured to engage with the adjacentvertebrae 2. The upper endplate 306 may include opposed side walls 312,314 and lower endplate 308 may include opposed side walls 316, 318. Theside walls 312, 314, 316, 318 may completely conceal or mostly concealthe internal expansion mechanism when the implant 300 is in thecollapsed configuration. Although not shown, the endplates 306, 308 mayhave teeth or friction enhancing surfaces and/or one or more graftwindows for receiving a graft material if desired.

The upper and lower endplates 306, 308 are mated with the upper andlower ramps 256, 258, respectively. The expansion mechanism works in thesame manner as described for implant 230. The front and rear drivingramps 252, 254 slidably interface with the upper and lower ramps 256,258. When the actuator 248 is rotated, the driving ramps 252, 254 forcethe upper and lower ramps 256, 258 away from one another, therebyexpanding the height of the upper and lower endplates 306, 308. Forexample, when the actuator 248 moves forward, the front driving ramp 252may move forward and the rear driving ramp 254 may move backward alongthe threaded portion 266 of the shaft 260 of the actuator 248. As thedriving ramps 252, 254 move away from one another, the height of theimplant 300 is increased.

The upper and lower endplates 306, 308 are able to passively pivot aboutthe longitudinal axis A of the implant 300, such that the endplates 306,308 are able to passively match the vertebral body endplate angles andminimize any edge loading. Similar to implant 230, the upper ramp 256may include a rounded portion 283 along an upper surface configured tomate with the upper endplate 306 and a rounded portion 283 along a lowersurface on the lower ramp 258 configured to mate with the lower endplate308. The rounded portion 283 may be received in a mating rounded recess294 defined within the upper and lower endplates 306, 308. In thismanner, the upper and lower endplates 306, 308 are configured to pivotabout the longitudinal axis A so that the implant 300 can passivelyaccount for the mismatch of the oblique angle of insertion and thedesired sagittal angle.

As shown in FIGS. 20A-20D, implant 300 may be implanted from an obliqueapproach similar to implants 20, 230. The spine may be accessedposteriorly. A cannula may be positioned on the disc space throughKambin's triangle, or the anatomical area that is bordered by the discspace, exiting nerve root, and traversing nerve root. The approach maybe oblique, for example, at about a 30° angle relative to a straightposterior access. The expandable interbody 300 is inserted in thecollapsed orientation. The expandable interbody 230 is then expanded inheight to precisely restore normal spinal alignment. The passivelongitudinal axis allows for the implant endplates 306, 308 to pivot tomatch the vertebral body endplate angles and minimize any edge loading.

The expandable fusion devices described herein may be manufactured froma number of biocompatible materials including, but not limited to,titanium, stainless steel, titanium alloys, non-titanium metallicalloys, polymeric materials, plastics, plastic composites, PEEK,ceramic, and elastic materials.

The features of the embodiments described herein may provide one or moreof the following advantages. A small insertion profile, such as a 10 mminsertion width into the disc space, may reduce skin, fascia, muscle,and/or ligamentous disruption. A controlled lordosis may be achievedthrough placement of the interbody in an articulated position on theanterior apophyseal ring. The interbody may continuously increaselordosis during expansion of the interbody. A reduced endplatedisruption may occur due to the expansion profile of the implant, andmay reduce the need for traditional trialing of interbody implants whichmay contribute to endplate disruption. The implant may passively adaptto the endplate profiles to maximize load distribution and minimize edgeloading and the associated subsidence. It will be appreciated thatdifferent or additional advantages may also be achieved based on thedisclosure herein.

It will be further understood that various changes in the details,materials, and arrangements of the parts which have been described andillustrated in order to explain the nature of this invention may be madeby those skilled in the art without departing from the scope of theinvention as expressed in the claims. One skilled in the art willappreciate that the embodiments discussed above are non-limiting. Itwill also be appreciated that one or more features of one embodiment maybe partially or fully incorporated into one or more other embodimentsdescribed herein.

What is claimed is:
 1. An expandable implant comprising: an upperendplate assembly including a plurality of upper endplates; a lowerendplate assembly including a plurality of lower endplates; an actuatorassembly including a rotatable actuator having a shaft and a rotatablenut; a plurality of driving ramps including a front ramp, a mid-ramp,and a rear ramp positioned along the shaft of the actuator; an upperramp connected to the upper endplate assembly and engaged with theplurality of driving ramps; and a lower ramp connected to the lowerendplate assembly and engaged with the plurality of driving ramps,wherein the upper and lower endplate assemblies are configured to expandin width, and wherein rotation of the actuator and/or the nut causesmovement of one or more of the driving ramps, thereby causing anexpansion in height of the upper and lower endplate assemblies.
 2. Theexpandable implant of claim 1, wherein the plurality of upper endplatesincludes a first upper outer endplate, a second upper outer endplate,and a third upper central endplate positionable between the first andsecond upper outer endplates, and wherein the plurality of lowerendplates includes a first lower outer endplate, a second lower outerendplate, and a third lower central endplate positionable between thefirst and second lower outer endplates.
 3. The expandable implant ofclaim 2, wherein the upper and lower central endplates are configured toexpand the respective upper and lower outer endplates outwardly, therebyexpanding the overall width of the implant.
 4. The expandable implant ofclaim 2, wherein one of the outer endplates includes an elongate grooveand the other outer endplate retains a pin configured to be receivedwithin the elongate groove, wherein when the outer endplates moveoutwardly, the pin is guided along the path of the elongate groove. 5.The expandable implant of claim 4, wherein the elongate groove is alinear groove that allows for a generally parallel expansion in width ofthe outer endplates.
 6. The expandable implant of claim 2, wherein thecentral endplates are configured to slide between the outer endplates onone or more tracks.
 7. The expandable implant of claim 6, wherein whenthe central endplates are advanced forward distally along the one ormore tracks, the outer endplates expand in width.
 8. The expandableimplant of claim 1, wherein the shaft of the actuator includes a firstthreaded portion, a second threaded portion, and a non-threaded portion.9. The expandable implant of claim 8, wherein the front ramp ispositioned on the non-threaded portion of the actuator, the mid-ramp ispositioned on the first threaded portion, and the rear ramp ispositioned on the second threaded portion.
 10. The expandable implant ofclaim 8, wherein the first threaded portion has a smaller outer diameterand different handedness than the second threaded portion.
 11. Theexpandable implant of claim 1, wherein the rotatable nut is configuredto move the rear ramp independent of the mid-ramp and front ramp. 12.The expandable implant of claim 1, wherein the upper and lower endplateassemblies are configured to passively pivot about a longitudinal axisof the implant.
 13. An implantable system comprising: an expandableimplant, the implant comprises an upper endplate assembly including afirst upper outer endplate, a second upper outer endplate, and a thirdupper central endplate positionable between the first and second upperouter endplates; a lower endplate assembly including a first lower outerendplate, a second lower outer endplate, and a third lower centralendplate positionable between the first and second lower outerendplates; an actuator assembly including a rotatable actuator having ashaft and a rotatable nut; a plurality of driving ramps including afront ramp, a mid-ramp, and a rear ramp positioned along the shaft ofthe actuator; an upper ramp connected to the upper endplate assembly andengaged with the plurality of driving ramps; and a lower ramp connectedto the lower endplate assembly and engaged with the plurality of drivingramps, wherein the upper and lower endplate assemblies are configured toexpand in width when the central endplates slide between the outerendplates, and wherein rotation of the actuator and/or the nut causesmovement of one or more of the driving ramps, thereby causing anexpansion in height of the upper and lower endplate assemblies, and aninserter instrument having a cannula configured for deploying theimplant into a disc space, wherein the cannula includes a pair ofopposed tabs configured to engage the implant to keep the implant fromadvancing too far into the disc space.
 14. The implantable system ofclaim 13, wherein the pair of opposed tabs include t-shaped tabsconfigured to mate with corresponding slots in sides of the implant. 15.An expandable implant comprising: a plurality of upper endplatesincluding a first plurality of links configured to articulate into agenerally polygonal shape; a plurality of lower endplates including asecond plurality of links configured to articulate into the generallypolygonal shape; an actuator assembly including a rotatable actuatorhaving a shaft; a plurality of driving ramps including a front ramp anda rear ramp positioned along the shaft of the actuator; an upper rampconnected to the plurality of upper endplates and engaged with theplurality of driving ramps; and a lower ramp connected to the pluralityof lower endplates and engaged with the plurality of driving ramps,wherein the plurality of upper and lower endplates are configured toexpand in width, and wherein rotation of the actuator causes movement ofone or more of the driving ramps, thereby causing an expansion in heightof the upper and lower endplates.
 16. The expandable implant of claim15, wherein the first and second plurality of links each include a frontlink and a rear link configured to mate with the upper and lower ramps,respectively.
 17. The expandable implant of claim 16, wherein the firstand second plurality of links expand in width when the rear links movetowards the front links.
 18. The expandable implant of claim 15, whereinthe shaft of the actuator includes a threaded portion and a non-threadedportion, wherein the front driving ramp is positioned on thenon-threaded portion of the actuator, and the rear ramp is positioned onthe threaded portion of the actuator.
 19. The expandable implant ofclaim 18, wherein rotation of the actuator causes the rear ramp to moveaway from the front ramp, which presses the upper and lower ramps awayfrom one another, thereby expanding the upper and lower endplates inheight.
 20. The expandable implant of claim 15, wherein the plurality ofupper and lower endplates are configured to passively pivot about alongitudinal axis of the implant.